Conventional servovalves convert relatively low power electrical control input signals into a relatively large mechanical power output. For example, during operation pressurized fluid enters the direct drive servovalve and, based upon the control input signals, drives a fluid actuator to operate variable-geometry elements such as associated with an aircraft.
A typical direct drive servovalve includes a housing, a valve member such as a spool, a motor, and a sensor. The housing defines a fluid pathway with the valve member being disposed within the fluid pathway. The motor is configured to move the valve member within the fluid pathway between an open and closed position in order to control an amount of fluid flow within the pathway. The sensor is configured to sense a position of the valve member within the fluid pathway and a rotational orientation of the motor's rotor assembly.
During operation, an electronic controller receives a command signal from a user input device which directs the controller to operate the servovalve in a particular manner (e.g., increase flow, decrease flow, terminate flow, etc.). The controller also receives a position signal from the sensor thus enabling the controller to determine the present position of the valve member within the fluid pathway. The controller then sends a control signal to the motor based on both the command signal and the position signal to control the rotational orientation of the rotor assembly. As a result, the rotor assembly moves the valve member to a desired position within the fluid pathway thus controlling amount of fluid flow relative to the fluid actuator.